Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

2018 GMC Terrain - New vehicle battery drain - where to start?

Major issues w/electrical system…battery drain

Start with dealer/warranty. Disclose any non-OEM electrical devices.


While you’re at it, ask the dealer whether there are any manufacturer’s “service advisories” for this vehicle, there may be something there that they’re not quite willing to admit to yet. Also look in a forum dedicated specifically to that vehicle.

They’re called “Technical Service Bulletins”. Or TSB’s

Don’t want to sound like an idiot.


Yes, I recall the Ford Taurus had 151 TSBs while in that same year the Lexus had only 4 TSBs.

Maybe I am. (Thanks). k

Car Complaints

      Discussion Alert!


    January 15

“service advisories”

They’re called “Technical Service Bulletins”. Or TSB’s

Technical Service Bulletin

Technical Service Bulletins, or TSBs, are recommended procedures for repairing vehicles. They are a form of diagnosis. Not to be confused with recalls, a TSB is issued by a vehicle manufacturer when there are several occurrences of an unanticipated problem. TSBs can range from vehicle-specific to covering entire product lines and break down the specified repair into a step-by-step process. While sometimes written by engineers employed by OEMs, the majority are authored by the first automotive tec…

Don’t want to sound like an idiot.


As posted above, best to not work on something like this yourself as it might void the warranty. If you insist to figure it out anyway, and don’t care about voiding the warranty or not, battery drain problems – I presume you mean the battery drains overnight when the GMC isn’t being used – these sorts of problems are usually addressed as the first step by measuring the current in the battery ground wire when everything should be turned off. Should measure in the 15-100 mA range, preferably no more than about 50 mA. It can take some time between when you shut of the engine and all the computers go to sleep, so give that an hour before you make the measurement.

If you feel lucky, forget measuring anything see if t here’s any unusual passenger compartment lighting behavior associated with the door switches. The computer may think somebody is opening the closing the doors all night, so it never goes to sleep. Check things like the glove compartment light, brake lights, engine compartment light etc, that they are all off when they should be.

Personally, the very first place I’d start is the dealers service department. Tell them to keep it until the problem is taken care of and supply an equivalent vehicle as a loaner until work is done. With major problems this soon after purchase make sure you keep detailed records of this and any subsequent work (warranty or not) just in case it is needed in the future.